Discussion
We encountered an OGIB patient who eventually experienced small intestinal stricture due to MD. The clinical course of this patient suggests two important clinical issues. First, although the frequency is low, OGIB patients may have small intestinal strictures due to inflammation from MD. Second, the diagnosis of bleeding due to MD is still sometimes difficult to determine, even when using several diagnostic modalities.
In the present case, intestinal stricture due to MD was diagnosed by BAE after the second occurrence of hematochezia. Although capsule retention was avoided with this patient, transient capsule retention inside the MD has been reported in other cases [10]. A possible explanation of the clinical course of the present case was that the bleeding from the ulcer in the ileum occurred; thereafter, stricture developed as a result of scar formation after ulcer healing. The ulcer formed due to exposure to acid secretion from the heterotopic gastric mucosa of MD. Because we performed CE after the second occurrence of hematochezia, there was a possibility that capsule retention might occur since the stricture was too severe to traverse with an enteroscope. More commonly, capsule retention due to drug-induced stricture from non-steroidal anti-inflammatory drugs has been reported, usually presenting as diaphragmatic stricture [11, 12]. Rezapour M et al. conducted a meta-analysis of retention associated with CE and reported that capsule retention occurred in 2.1% of patients with OGIB [9]. Furthermore, 3% of patients with capsule retention in that meta-analysis developed obstructive symptoms. Patency CE is used for patients who have a high risk of intestinal stricture, and reports indicate that it has reduced the risk of capsule retention by half with IBD patients [9]. Performing patency CE for all OGIB patients is not recommended, considering the low incidence of stricture due to MD (such as our case), but endoscopists should keep in mind the possibility of stricture due to MD when examining OGIB. If the possibility of MD is already high with other modalities, patency CE may be an option before CE.
It was difficult to diagnose MD before surgery with the present case. Several specific diagnostic tools have been reported to help diagnose MD, including arteriography, technetium 99m pertechnetate scan, CE, and BAE. Among these, arteriography and technetium 99m pertechnetate scan are regarded as the standard tools to diagnose MD. If bleeding is heavy, arteriography can be a good option. In patients who have less bleeding, high-resolution CT arteriography can be a good option, and its overall sensitivity for detecting active acute GI bleeding is reported to be as high as 85.2 % [13]. If bleeding stops spontaneously, it could be difficult to detect the source of bleeding with high-resolution CT arteriography. The technetium 99m pertechnetate scan failed to diagnose the presence of MD with the present case, although the heterotopic gastric mucosa was confirmed pathologically after surgery. The sensitivity of the technetium 99m pertechnetate scan for adult MD has been reported to be approximately 60% [6]. Krstic SN et al. reported that CE had a high positive predictive value of 84.6 % for the diagnosis of MD [4]. However, in the same study, CE identified the source of bleeding in only 44.6% of OGIB patients. In the present case, several diagnostic tools, including high-resolution CT arteriography, technetium 99m pertechnetate scan, and CE, failed to diagnose MD. Considering the insufficient sensitivity of some tests to diagnose MD, several examinations, including BAE, should be carried out to diagnose MD. Although BAE is an invasive procedure, it could be sometimes a preferable option compared with other modalities, especially for the diagnosis of MD [5, 14].
In addition to the difficulty of MD diagnosis, we should keep in mind the possibility of intestinal stricture due to MD when seeing OGIB patients.